As one skilled in this field of technology appreciates, vanes have sundry uses in devices requiring fluid flows such as inlet guide vanes, stator vanes, turbine nozzle guide vanes, etc., where it is desirable to either impart a swirl to the fluid, remove the swirl from a fluid, and guide the flow into the rotating compressor or turbine, for guiding air into a combustor, etc. Obviously, the fluid medium can take the form of liquid, gas, etc. While this invention is particularly concerned with the vanes that are utilized in an annular configuration, it will be appreciated from the description to follow that these vanes and the construction thereof has utility in many applications.
When utilized in a burner application, particularly of the annular type of burner utilized in gas turbine engines, one skilled in this art will appreciate that in order to sustain combustion a recirculating zone is required and the recirculating zone is located in proximity to where ignition of the fuel/air mixture in the primary zone of the burner and combustion ensues. The primary zone assures continuous combustion after the igniter has been shut down although, in certain applications a continuous igniter remains during the complete operations of the burner. In some burners, for example, in an annular combustor utilized in microturbine engines manufactured by Elliott Energy Systems, Inc., the assignee of this patent application, the combustor utilizes a dam that extends inwardly toward the center line of the combustor. Air is admitted into the combustor through the vanes formed in the dam in proximity to the primary combustion zone, so that this air together with a small amount of air admitted therein in openings formed in the combustion liner adjacent to the fuel nozzles (that extend into the primary combustion zone) serve to define the recirculating zone. In the annular combustor of this mini jet engine the dam/vanes are mounted at the outer portion of the annular combustion zone or toward the outer combustor liner and the dam/vanes are mounted at the inner portion of the annular combustion zone or towards the inner combustion liner. In this application, the dam is made from two annular members, a forward facing annular member and a rearward facing annular member and the vanes are mounted therebetween. In other words, the vanes are circumferentially spaced defining a ring-like configuration. In fabricating the dam/vane configuration, each of the plurality of vanes are individually fabricated and are assembled in their respective positions sandwiched between the fore facing annular member and the aft facing annular member and this assembly is brazed forming a integral unit. This assembly can be fabricated in this manner before being mounted into the annular combustor or the assembly can be fabricated while held in the annular combustor. In either process, the assembly of the vanes in this manner is cumbersome, time consuming and obviously, expensive.
I have found that I can fabricate the dam/vane assembly by fabricating dam/vane in a much improved manner, making the process less cumbersome, requiring less time to assemble and less expensive. In accordance with this invention the vane member includes an inner set of circumferentially spaced vanes and an outer set of circumferentially vanes held together by a hub defining a unitary unit. Both annular members of the dam are separately fabricated and are mounted so as to sandwich the vane/hub structure and brazed together to define an integral assembly. This assembly is then cut, removing the hub portion from the vanes and the complementary contiguous portions of the two dam members, thus leaving a torroidally shaped member with an annular passage way. The sets of vanes define air inlets for the outer portion of the liner and the inner portion of the liner.
It is apparent from the foregoing, that this is an improved method for fabricating a dam/vane unit and an annular combustor assembly, but it is also apparent to one skilled in this technology, that this method lends itself to the fabrication of other vane products. For example, the combustor described above can be fabricated with a single ring of vanes in either the outer dam or inner dam. The vane construction needn't be limited to an annular combustor. The vane constructed in accordance with this invention includes multi-options. The vanes need not be configured in a ring type of configuration, or the ring may be disposed at an angle relative to the center-line rather than being perpendicular thereto, the vane configuration can take many forms of mechanical configurations, as for example, a cone or a linear shape. What is important is that each of the vanes are held in position by a superficial material that serves to hold the vanes in position while being assembled and affixed in place and the superficial material is then removed. The vanes/superficial material configuration can by itself be a product that is manufactured and sold to others for use in their own products. These examples described in the immediate above paragraphs are merely used for explanation purposes and are not intended to be a limitation to the scope of this invention.